Process for recovery of tocopherols and sterols



United States Patent Office ib hi h Patented Oct. 22, 1963 3,108,120PROQESS FOR RECKJVERY OF TUCGPHEROLS AND STERULS Winton Brown and KariH. Meng, Rochester, N.Y., as-

signors to Eastman Kodak Company, Rochester, N .Y., a corporation of NewJersey No Drawing. Filed Feb. 23, 1961, Ser. No. 90,933 7 Claims. (til.260345.6)

This invention relates to the chemical arts. More particularly, itrelates to an improvement in the lime soap process for recoveringtocopherols and a sterols from vegetable oil and animal oil deodorizerdistillates and the like.

The lime soap process for the treatment of materials containingtocopherols and sterols is well known in the art. One embodiment of thisprocess is taught by Rossouw and Von Rudloff (J. Applied Chemistry,2,335- 338, June 1952), who disclose lime saponification of wool waxfollowed by extraction of the unsaponifiable fraction with acetone inwhich the lime soaps are insolule. Another embodiment of this process isdisclosed by Hickman in his US. Patent, No. 2,349,270, wherein siakedlime is added to a deodorizer distillate and the resulting lime soapmass broken up and extracted with ethyl ether. Still another embodimentis taught by Andrews in US. Patent No. 2,263,550. This patent disclosesthe saponification of a vegetable oil distillation residue containingvitamin E, followed by metathesis with calcium chloride to form calciumsoaps which are then extracted with acetone to recover unsaponifiablematter. The unsaponifiable matter in each case comprises tocopherols andsterols.

When applying this process in any of its embodiments to vegetable oildeodorizer distillates and the like having a high concentration ofunsaponifiable matter, a hard, wax-like gel between the soaps andunsaponifiable matter forms. This gel is difficult to leach withsolvents for the tocopherols and sterols because of the relatively smallsurface of the gel or soap exposed to solvent action. Consequently, itis necessary to subdivide the soap into extractable form. This calls forheavy grinding or masticating machinery. Moreover, a large number ofsolvent extraction steps subsequently must be employed. Not only issolvent consumption or loss high but the yield of tocopherols andsterols is low. Hence, the lime soap process, when applied to vegetableoil deodorizer distillates and the like having a high concentration ofunsaponifiable matter, is inherently uneconomical and requires asubstantial capital investment. There is, therefore, a need forimprovement of the lime soap process. A general object of this inventionis to provide such an improvement.

More particularly, an object of this invention is to so improve the limesoap process that a subdivided soap in extractable form is obtained fromdeodorizer distillates and the like having a high concentration ofunsaponifiable matter without the necessity of employing heavy grindingor masticating machinery.

Another object of this invention is to so improve the lime soap processthat a subdivided soap is provided which requires a minimum number ofsolvent extraction steps to give high yields or recoveries oftocopherols and sterols with a minimum of solvent consumption.

These and other objects which may appear as this specification proceedsare achieved by this invention.

This invention, in summary, involves an improved lime soap processcharacterized by the presence of a powdering agent in the lime soap masswhile extracting unsaponifiable matter therefrom with a selectivesolvent, a solvent in which tocopherols and sterols are soluble and thelime soaps are insoluble.

The powdering agent, which might also be called an extraction aid, is afinely divided, oil adsorbent, abrasive, inorganic solid insoluble inthe solvent and inert relative to the components of the lime soap mass.Preferably the powdering agent is of colloidal particle size in order toprovide adequate surface contact between the soap mixture and theextraction solvent. While inorganic solids of particle sizes larger thancolloidal can be employed, they are not very efficient as powderingagents. A particularly efficacious powdering agent is colloidal calciumsilicate. Other powdering agents that can be used are colloidal sodiumsilico-aluminate, finely divided alumina, colloidal silica and colloidaltitania. Pulverized sodium sulfate and diatomite, for example, are notrecommended because of the larger than colloidal particle size of thesolids thereof. For this reason they are comparatively inefficient aspowdering agents.

The powdering agent is introduced into the lime soap mass preferablywhile the soap mass is fluid or flowable and when the moisture contentof the lime soap mass is, and will continue to be, preferably less thanabout five percent by weight of the lime soap mass, ideally at zeroweight percent. It is necessary that the soap mass be fluid or at leastplastic when the powdering agent is added because once the lime soapmass has set into a hard gel, addition of the powdering agent has nosignificant effect. The moisture content of the lime soap mass isanother important factor in this invention. If too much moisture ispresent the powdering agent does not work properly. This is due probablyto a preferential wetting of the powdering agent by water.Investigations have shown that the moisture concentration in the limesoap mass should preferably not exceed about five percent by weight ofthe mass. Hence, when these two conditions are present the powderingagent can be introduced into the lime soap mass during its formation(with the addition of the calcium ion bearing reagent to the saponifiedsludge) and it can be introduced into the lime soap mass at the solventextraction step. Usually, however, it will be introduced into the limesoap mass after the mass has been subjected to a partial dryingoperation prior to the solvent extraction step. Introduction of thepowdering agent to the lime soap mass is accomplished by admixture untilthe powdering agent is uniformly dispersed throughout the mass.

The concentration of the powdering agent in the lime soap mass shouldlie in a range from about 3 Weight percent to about 21 weight percent.At a concentration less than about 3 weight percent the powdering agentdoes not produce any significant effect while at a concentration greaterthan 21 weight percent no additional improvement can be ascertained.Usually, the concentration of the powdering agent will be in a practicaloptimum range from about 6 weight percent to about 10 weight percent.

The powdering agent functions under the conditions of this invention tosubdivide the lime soap mass at least in the presence of the extractionsolvent into small discrete particles and ideally into a frangiblepowder. The reasons why the powdering agent functions this way are notfully known. However, it is believed that the powdering agent functionsthrough the creation of interfacial forces which tend to override thenatural cohesive forces of the soap mixture. This explains the need forrelatively dry soap to provide adequate wetting of the powdering agentby lipid matter. It appears possible that the abrasive quality of theinorganic powdering agent also plays a role in breaking up any lumpymaterial that is formed.

A preferred embodiment of the improved lime soap process of thisinvention is one wherein the lime soaps are formed by the metathesis ofsaponified deodorizer distillates with an inorganic calcium materialsuch as a water solubie salt, for example, calcium chloride, and such ascalcium oxide, calcium hydroxide or the like. In general this embodimentof the process proceeds as follows.

Crude vegetable oil deodorizer distillate, rich in unsaponifiablematter, is saponified in an alcoholic medium with an excess of an alkaliwhich is an alkali metal tincluding ammonium) hydroxide, carbonate andthe like, (preferably a 50% aqueous solution of sodium hydrox: ide).When saponification is complete, the excess alkali is neutralized with adilute mineral acid. This provides an environment more favorable to thepreservation of the tocopherols throughout the remaining steps of theprocess.

At this point a quantity of an aqueous solution of a calcium salt,preferably calcium chloride, is admixed with the mass. This quantitypreferably represents a stoichiometric excess to the extent of about ofthe quantity required to convert the sodium soaps into calcium soaps.Additional monohydric alcohol, such as methanol, is added to thereaction mass. This tends to prevent emulsification which would mitigateagainst a clean separation of the water soluble components. The reactionmass is permitted to settle, whereupon two layers form.

The aqueous, alcoholic, salt layer containing the glycerine ofsaponification is decanted from the underlying layer of calcium soapscontaining the unsaponifiables which, at this point, still form arelatively fluid mass. The soaps are then heated to a temperature inexcess of 100 C. until any remaining alcohol is vaporized and theresidual water concentration of the soap mass is less than about fiveweight percent.

The inorganic powdering agent is then admixed with the still fluid soapmass.

The soap mass may then be subjected to further heat and vacuum to driveoff the remaining volatile matter. At this point, the soaps may becomerather tacky but upon addition of the extraction solvent, the tacky masssoon disintegrates into a friable powder.

An extraction solvent, preferably acetone, is admixed with the soapmass-powdering agent mixture, forming a slurry. The unsaponifiablematter is released from the mixture and dissolved in the solvent.

The extracted slurry is then filtered (readily) through a pressure orsuction filter and the filter cake treated with fresh solvent to removeoccluded unsaponified matter by insing, repulping and reextraction or byboth of these methods.

The combined extract and washes are concentrated as by solventdistillation and wintered at low temperatures in order to crystallizethe sterols. The crystallized sterols are then readily removed byfiltration to give a high purity sterol fraction and in the filtrate ahigh potency tocopherol fraction.

The original mare containing the powdering agent and calcium soaps isthen acidulated with dilute mineral acid, for example, hydrochloricacid, in order to generate a high purity fatty acid fraction relativelyfree of unsaponifiables. The aqueous layer from the acidulationcontaining in solution the calcium salt of the mineral acid, forexample, calcium chloride, can be filtered to recover for reuse theundissolved powdering agent.

In another preferred embodiment of the improved lime soap process ofthis invention the lime soaps are formed directly. In this embodimenteither calcium oxide and at least a stoichiometric quantity of water orcalcium hydroxide plus a small amount of water are admixed with thecrude vegetable oil deodorizer distillate and the mixture heated toabout 200 C. for a suitable reaction time, for example, 1 hour in anenclosed reaction vessel under elevated pressure. At the end of thereaction time the reaction mass is brought to atmospheric pressure and,if necessary, excess moisture evaporated to establish the moistureconcentration of the reaction mass at less than about five weightpercent. The inorganic powdering agent is then admixed with the reactionmass. Extraction and work-up of the extract and mare is then done in thesame fashion as in the case of the metathesis embodient of thisinvention.

Various concepts, advantages and features of this invention arepresented in the following examples. In this regard these examples areillustrative and not restrictive.

Example 1 This example illustrates the application of the concepts ofthis invention to the metathesis embodiment of the lime soap process.

300 grams of soybean oil deodorizer distillate having a 12.3 weightpercent total tocopherol content as ascertained by Emmerie-Engel assay,approximately 17 weight percent total sterol content as determined byinfrared assay and having a saponification number of 119 were dissolvedin 230 milliliters of methyl alcohol in a stirred reactor and heated toreflux temperature. After air had been expelled from the reactor andwhile the solution was under reflux, 67 grams of 48% aqueous sodiumhydroxide were gradually added to the reactor contents. Saponificationresulted. Reflux conditions were continued for approximately 1 hour tocomplete the saponification. 13.2 milliliters of 37% hydrochloric acidwere then added to the saponified mixture to neutralize the excesssodium hydroxide.

A solution containing 51 grams of calcium chloride, 200 milliliters ofwater and 700 milliliters of methyl alcohol was then stirred into thesaponified mixture. Immediately a thick, creamy layer of calcium soapsformed on the bottom of the reactor containing the mixture. A relativelyclear alcohol and water layer formed on top of the calcium soaps layer.The alcohol and water layer containing glycerin, sodium chloride andexcess calcium chloride was removed by decantation.

The remaining soap mass was dried to a moisture concentration less thanabout 5 weight percent by stirring and heating to a temperature of 100C. at atmospheric pressure.

At this point 10 grams of colloidal calcium silicate, commericallyavailable under the proprietary designation of Microcel C were stirredinto the still fluid soap mass. The mixture was heated under vacuum withstirring to remove the last visible traces of alcohol and water. Thisresulted in the soap mixture becoming solid due to evaporative cooling.The vacuum was broken with nitrogen and 1 liter of boiling acetoneadded. In approximately 5 minutes the solid soap mixture disintegratedinto small particles. The boiling acetone-soap mixture was stirred for 1hour. The resulting slurry was cooled slightly and then filtered on aBiichner type filter with moderate suction. The filter cake was rinsedin situ with a small amount of hot acetone and reextracted once morewith 1 liter of boiling acetone to remove the last traces ofunsaponifiable material.

The actone extracts were combined, concentrated by distillation to avolume of 600 milliliters and chilled overnight to a temperature of 20C. whereby a sterol fraction crystallized. The crystalline sterolfraction was removed by filtration and then dried, weighed and analyzed.There were 43 grams dry weight of pure white crystalline solids assayingby infrared by weight free sterol. This represents 78% by weight of theinput sterols.

The filtrate was distilled to give a tocopherol concentrate. Theconcentrate was weighed and analyzed. There were 63.8 grams ofconcentrate assaying by the Emmeric- Engel assay method 51 weightpercent tocopherol. This represents a yield of 88.3%.

The mare was acidulated with an excess of sulfuric acid. An oil layerand a water layer formed. Analysis of the oil layer showed an acid valueof 180, 3.5 Weight percent total sterols as determined by infrared assayand 0.1 weight percent tocopherol as determined by Emmeric- Engel assay.

Example 2 This example illustrate the improvement obtained by employinga powdering agent accordance with this invention in the lime soapprocess.

300 grams of soybean oil deodorized distillate were saponified,neutralized and converted to lime soaps as in Example 1. The wet soapswere dried to a moisture content less than about 5 weight percent byheating to a temperature of 100 C. and then placed under vacuum. Theresultant mass became solid in appearance.

1 liter of boiling acetone was added to the plastic soap mass andstirred under reflux conditions. A large soap ball formed under theaction of the stirring device and there was no evidence of break-up ofthe soap mass even after continuous stirring and refluxing of theacetone for a period of 30 minutes.

20 grams of Microcel C colloidal calcium silicate were added to thereactor contents. Immediately the plastic soap ball began to break upand after minutes was completely disintegrated.

The resulting slurry was stirred in the acetone for 1 hour. The slurrywas then filtered and reextracted twice, using 1 liter of boilingacetone for each extraction. From this point on the filtrate or micellawas treated as in Ex ample 1. There resulted 37.5 grams of pure whitesterols (99% pure by infrared analysis) at a yield of 71%, 62 grams oftocopherol concentrate (51% pure by Emmeric- Engel response)representing a yield of 85.6% and an acidulated mare with an acid valueof 198 with the unsapcnifiables comprising mainly 4.5 weight percentsterols and 0.4 weight percent tooopherol.

Example 3 This example illustrates the eifect of too much water beingpresent in the lime soap mass upon the addition of the powdering agent.

300 grams of soybean oil deodorizer distillate were saponified,neutralized and converted to lime soaps as in Example 1. The lime soapswere partially dried by heating to a temperature of 100 C. withoutemploying vacuum degassing. The soaps at this point were found to stillcontain 6.3 weight percent volatile matter, mostly water. 1 liter ofboiling acetone was added to the mass. 28 grams of Microcel C colloidalcalcium silicate was added and the mixture stirred. The soaps soonturned to a heavy grease with was very difiicult to stir, tended tostick to the sides of the reactor and to ball up on the stirring device.Additional Microcel C colloidal calcium silicate was added untilappreciable breakup of the soap mass was observed. This amounted toabout 60 grams of calcium silicate. This partial breakup resulted inrather large agglomerated particles which were not efficientlyextracted.

Example 4 This example illustrates the fact that in the procedure ofExample 3, if there is too much moisture present, it makes no differencein the end result if the powdering agent is added before or after theselective solvent.

The procedure of Example 3 was repeated except that that 20 grams ofMicrocel C colloidal calcium silicate were first added to the partiallydried lime soaps and then 1 liter of boiling acetone was added. The sameresults were obtained as in Example 3.

Thus, there is provided an improved lime soap excess especially usefulfor recovering tocopherols and sterols from vegetable oil deodori-derdistillates and the like having a high concentration of unsaponifiablematter. By the lime soap process of this invention lime soaps areobtained which are readily extractable with a selective solvent inordinary processing equipment with a better yield of tocopherols andsterols with few selective solvent extractions and less selectivesolvent consumption.

Other advantages, features and embodiments will be readily apparent tothose in the exercise of ordinary skill in the art upon reading theforegoing specification. In

6 this regard all embodiments of this invention including variations andmodifications thereof embracing the spirit and essential characteristicsof this invention are within the scope of the claimed subject matterunless expressly excluded by claim langauge.

We claim:

1. In the lime soap process for treating vegetable oil deodor-izerdistillates and the like to recover unsaponifiable matter includingsterols and tocopherols therefrom, wherein a lime soap mass containingsaid unsaponifiable matter is formed and then extracted with a selectivesolvent in which the lime soaps are insoluble and the unsaponifiablematter is soluble, the improvement which comprises: introducing intosaid lime soap mass before it sets into a hard gel a powdering agent ina quantity sufficient to cause break-up of said mass upon extractionwith said solvent, said powdering agent being a finely divided, oilabsorbent, abrasive, inorganic solid insoluble in said solvent and inertrelative to the components of the lime soap mass.

2. In the lime soap process for treating Vegetable oil dcodonizerdistillates and the like to recover unsaponifiable matter includingsterols and tocopherols therefrom, wherein a lime soap mass containingsaid unsaponifiable matter is formed and then extracted with a selectivesolvent in which the lime soaps are insoluble and the unsaponifiablematter is soluble, the improvement which comprises: establishing andmaintaining the moisture content of said li-me soap mass below aboutfive percent by weight; and admixing with the lime soap mass before itsets into a hard gel at powdering agent selected from the groupconsisting of colloidal calcium silicate, colloidal sodiumsiiico-aluminate, finely divided alumina, colloidal silica and colloidaltitania, the concentration of said powdering agent in said mass being ina range from about 3 percent by weight to about 21 percent by weight.

3. in the lime soap process for treating vegetable oil deodorizerdistill-ates and the like to recover unsaponifiable matter includingsterols and tocopherols therefrom, wherein a lime soap mass containingsaid unsaponifiable matter is formed and then extracted with a selectivesolent in which the lime soaps are insoluble and the unsaponifiablematter is soluble, the improvement which comprises: establishing andmaintaining the moisture content of said lime soap mass below about fivepercent by weight; and admixing with the lime soap mass before it setsinto a hard gel a powdering agent selected from the group consisting ofcolloidal calcium silicate, colloidal sodium silico-aluminate, finelydivided alumina, colloidal silica and colloidal titania, theconcentration of said powdering agent in said mass being in a range fromabout 6 percent by weight to about 10 percent by weight.

4. in the lime soap process for treating vegetable oil deodorizerdistillates and the like to recover unsaponifiable matter includingsterols and tocopherols therefrom, wherein a lime soap mass containingsaid unsaponifiable matter is formed and then extracted with a selectivesolvent in which the lime soaps are insoluble and the unsapon-ifiablematter is soluble; the improvement which comprises: establishing andmaintaining the moisture content of said lime soap mass below about fivepercent by weight; and admixing with the lime soap mass before it setsinto a hard gel colloidal calcium silicate, the concentration of saidcolloidal calcium silicate in said mass being in a range from about 6percent by weight to about 10 percent by weight.

5. A process for treating a vegetable oil deodorizer distillate and thelike to recover sterols and tocopherols therefrom, which comprises:saponifying saponifiable matter in said distillate with an alkali;admixing with the saponified matter an inorganic calcium materialwhereby a lime soaps mass is formed; removing from the lime soaps masswater-soluble matter and suflicient water to establish the lime soapsmass at a water concentration less than about five weight percent;admixing with the 2,, lime soaps mass while still fluid a powderingagent selected from the group consisting of colloidal calcium silicate,colloidal sodium silico-aluminate, finely divided alumina, colloidalsilica and colloidal titania, the concentration of said powdering agentin said lime soaps mass being in a range from about 3 weight percent toabout 21 weight percent; admixing with the lime soaps mass-powderingagent mixture a selective solvent in which the lime soaps are insolubleand sterols and tocopherols are soluble whereby a solvent solution ofsaid sterols and tocopherols is formed; separating said solution fromsaid mixture; and recovering powdering agent from said mixture.

6. A process for treating a vegetable oil deodorizer distillate and thelike to recover sterols and tocopherols therefrom, which comprises:saponifying saponifiable matter in said distillate with sodiumhydroxide; admixing with the saponified matter an aqueous solution of acalcium salt whereby a lime soaps mass is formed; removing from the limesoaps mass water-soluble matter and sulficient water to establish thelime soaps mass at a water concentration less than about five weightpercent; admixing with the lime soaps mass while still fluid colloidalcalcium silicate, the concentration of said colloidal calcium silicatein said lime soaps mass being in a range from about 3 Weight percent toabout 21 weight percent; admixing with the lime soaps mass-colloidalcalcium silicate mixture a selective solvent in which the lime soaps areinsoluble and sterols and tocopherols are soluble whereby a solventsolution of said sterols and tocopherols is formed; separating saidsolution from said mixture; and

removing solvent from said solution whereby a concentrate of sterols andtocopherols is obtained.

7. A process for treating a vegetable oil deodorizcr distillate and thelike to recover sterols and tocopherols therefrom, which comprises:saponifying saponifiable matter in said distillate with sodiumhydroxide; admixing with the saponified matter an aqueous solution ofcalcium chloride whereby a lime soaps mass is formed; removing from thelime soaps mass water-soluble matter and sufficient water to establishthe lime soaps mass at a water concentration less than about five weightpercent; admixing with the lime soaps mass while still fluid colloidalcalcium silicate, the concentration of said colloidal calcium silicatein said lime soaps mass being in a range from about 3 weight percent toabout 21 weight percent; admixing with the lime soaps mass-colloidalcalcium silicate mixture a selective solvent in which lime soaps areinsoluble and stero-ls and tocopherols are soluble whereby a solventsolution of said sterols and tocopherols is formed; separating saidsolution from said mixture; and recovering colloidal calcium silicatefrom said mixture by aciditying said mixture with a dilute mineral acidwhereby there is formed a fatty acid fraction and an aqueous fractionand separating from said aqueous fraction said colloidal calciumsilicate.

References Cited in the file of this patent UNITED STATES PATENTS

2. IN THE LIME SOAP PROCESS FOR TREATING VEGTABLE OIL DEODORIZERDISTILLATES AND THE LIKE TO RECOVER UNSAPONIFIABLE MATTER INCLUDINGSTEROLS AND TOCOPHEROLS THEREFROM, WHEREIN A LIME SOAP MASS CONTAININGSAID UNSAPONIFIABLE MATTER IS FORMED AND THEN EXTRACTED WITH A SELECTIVESOLVENT IN WHICH THE LIME SOAPS ARE INSOLUBLE AND THE UNSAPONIFIABLEMATTER IS SOLUBLE, THE IMPROVEMENT WHICH COMPRISES: ESTABLISHING ANDMAINTAINING THE MOISTURE CONTENT OF SAID LIME SOAP MASS BELOW ABOUT FIVEPERCENT BY WEIGHT; AND ADMIXING WITH THE LIME SOAP MASS BEFORE IT SETSINTO A HARD GEL A POWDERING AGENT SELECTED FROM THE GROUP CONSISTING OFCOLLOIDAL CALCIUM SILICATE, COLLODIAL SODIUM SILICO-ALUMINATE, FINELYDIVIDED ALUMINA, COLLOIDAL SILICA AND COLLOIDAL TITANIA, THECONCENTRATION OF SAID POWDERING AGENT IN SAID MASS BEING IN A RANGE FROMABOUT 3 PERCENT BY WEIGHT TO ABOUT 21 PERCENT BY WEIGHT.